1. Field of the Invention
The present invention relates to a system and method for oil fuel burning integrated combined cycle power generation.
2. Description of the Related Art
In the integrated combined cycle power generation where oil fuel is burned for the power generation, the power generation is carried out by rotating a gas turbine using combustion gas obtained by burning fuel gas and the power generation is further carried out by rotating a steam turbine with steam which is produced by recovering waste heat from high-temperature exhaust gas discharged from the gas turbine. This type of the integrated combined cycle power generation can achieve the thermal efficiency of about 49% in gross heating value to realize the effective utilization of the energy.
A technique of combining a power generation system for carrying out such integrated combined cycle power generation and a fuel producing system for producing gas turbine fuel oil is described in JP-A-9-189206 and so on. For example, JP-A-189206 describes that in the fuel producing system, crude oil is distilled to be separated into a low boiling point fraction and a high boiling point fraction and the low boiling point fraction is fed to a fuel oil tank using a pump, then the fuel oil is sent from the tank to a combustor of a gas turbine system in the power generation system via a transport line to drive a gas turbine, while the high boiling point fraction is used as boiler fuel for driving a steam turbine.
On the other hand, for producing as much power as possible from one unit calorie of feed oil, it is necessary to draw light oil for a gas turbine from the feed oil at high rate. However, if the light oil is extracted at the high rate, residue oil becomes highly viscous, and further, the contents of impurities, e.g. heavy metal such as vanadium, and sulfur, increase.
When the residue oil containing much heavy metal is used as boiler fuel, the flame temperature of a burner in a boiler increases up to about 1300xc2x0 C. which exceeds melting temperatures of the impurities such as vanadium contained in the residue oil. Among the melted impurities, melted vanadium which adheres to a metal surface of the inside of the, boiler causes high-temperature corrosion. Accordingly, when high-impurity residue oil containing, for example, vanadium no less than 100 ppm is used as boiler fuel, it is necessary to prepare a boiler combustion furnace with a special structure which can prevent an occurrence of excessively-high-temperature portions, whose volume is large enough and where it is necessary to add a neutralizer such as magnesium upon burning the boiler fuel. Thus, there is raised a cost problem, such as an increase in operation cost and construction cost.
Further, the efficiency of the boiler power generation using the residue oil is as low as 40% or less which is lower than that of the general gas turbine power generation. Therefore, even if the light oil obtained from the feed oil is used as fuel for the gas turbine power generation and the residue oil (heavy oil) is used as fuel for the boiler power generation, the total efficiency only becomes as low as about 44% to 48%.
Therefore, it is an object of the present invention to provide an improved oil fuel burning integrated combined cycle power generation system which can effectively utilize feed oil to carry out power generation.
It is another object of the present invention to provide an improved oil fuel burning integrated combined cycle power generation method which can effectively utilize feed oil to carry out power generation.
According to one aspect of the present invention, there is provided an oil fuel burning integrated combined cycle power generation system comprising: a fuel producing system comprising a separation means for separating feed oil composed of a crude oil and/or heavy oil into a light portion and a heavy portion, and a refining means for refining the light portion to obtain fuel oil; a gasification system for gasifying the heavy portion to produce syngas containing hydrogen gas and carbon monoxide gas; a gas turbine power generation system for driving a gas turbine using the fuel oil and the syngas as fuel to carry out power generation; and a steam turbine power generation system for driving a steam turbine using steam produced by heat recovered from exhaust gas of the gas turbine to carry out power generation.
It may be arranged that the fuel producing system comprises a tank for storing the fuel oil, and the gas turbine power generation system requires a constant supply of the syngas from the gasification system as basic fuel and further requires a supply of the fuel oil from the tank as auxiliary fuel for adjusting a power generation amount depending on power demand.
It may be arranged that the separation means comprises a distillation means and a solvent deasphalting means, and that the refining means comprises a hydrotreating unit for refining the light portion to satisfy a gas turbine fuel specification.
It may be arranged that the gas turbine power generation system comprises a compressor connected to the gas turbine for producing compressed air to be fed to a combustor of the gas turbine, and that the gasification system carries out partial oxidation of the heavy portion using the compressed air fed from the compressor.
It may be arranged that the oil fuel burning integrated combined cycle power generation system further comprises an oxygen separation unit provided between the gas turbine power generation system and the gasification system, wherein the gas turbine power generation system comprises a compressor connected to the gas turbine for producing compressed air to be fed to a combustor of the gas turbine, wherein the oxygen separation unit carries out low-temperature separation of oxygen from part of the compressed air fed from the compressor, and wherein the gasification system carries out partial oxidation of the heavy portion using oxygen fed from the oxygen separation unit.
It may be arranged that the oil fuel burning integrated combined cycle power generation system further comprises an oxygen producing unit for separating oxygen from air using a pressure swing adsorption method, wherein the gasification system carries out partial oxidation of the heavy portion using oxygen fed from the oxygen producing unit.
It may be arranged that the separation means comprises a distillation means and a solvent deasphalting means, that the heavy portion fed to the gasification system is a residue separated by the solvent deasphalting means from a heavy portion of the feed oil obtained by the distillation means, and that the residue is uniformly dispersed into water and fed to the gasification system as water slurry fuel.
It may be arranged that the gas turbine power generation system has a power generation capacity which is greater than a power generation amount obtainable by using all the amount of the syngas produced in the gasification system.
It may be arranged that the gas turbine power generation system carries out mixed combustion of the fuel oil in a liquid phase and the syngas in a gaseous phase.
It may be arranged that the, gas turbine power generation system comprises a plurality of gas turbines including the gas turbines each driven by the syngas and the gas turbines each driven by the fuel oil.
It may be arranged that the syngas is constantly fed to the corresponding gas turbines as basic fuel, while the fuel oil is fed to the corresponding gas turbines as auxiliary fuel for adjusting a power generation amount depending on power demand.
According to another aspect of the present invention, there is provided an oil fuel burning integrated combined cycle power generation method comprising: a fuel producing step of separating essentially all the amount of feed oil composed of a crude oil and/or heavy oil into a light portion satisfying a gas turbine fuel specification and a heavy portion being a residue of the feed oil after separation of the light portion therefrom; a gasification step of gasifying essentially all the amount of the heavy portion through partial oxidation to produce syngas containing hydrogen gas and carbon monoxide gas; a gas turbine power generation step of carrying out power generation based on essentially all the amount of the syngas supplied as basic fuel and further based on the light portion supplied as auxiliary fuel for adjusting a power generation amount depending on power demand; and a steam turbine power generation step of carrying out power generation using steam produced by high-temperature exhaust gas obtained in the gas turbine power generation step.
It may be arranged that the gasification step disperses the heavy portion into water uniformly to form water slurry fuel when the heavy portion obtained in the fuel producing step has a softening point higher than 140xc2x0 C., and then gasifies the water slurry fuel to produce the syngas, that the gasification step forms the heavy portion into emulsion fuel when the softening point is higher than 110xc2x0 C. and no higher than 140xc2x0 C., and then gasifies the emulsion fuel to produce the syngas, and that the gasification step keeps the heavy portion as it is in a high-temperature state when the softening point is no higher than 110xc2x0 C., and then gasifies the heavy portion to produce the syngas.
It may be arranged that the fuel producing step comprises a distillation separating step, a solvent deasphalting separation step and a refining step for refining through a hydrotreatment the light portion obtained through the distillation separating step and the solvent deasphalting separation step.
It may be arranged that the gasification step uses compressed air produced in the gas turbine power generation step to carry out the partial oxidation.
It may be arranged that the oil fuel burning integrated combined cycle power generation method further comprises the step of producing oxygen through low-temperature separation from compressed air produced in the gas turbine power generation step, wherein the gasification step carries out the partial oxidation using the produced oxygen.
It may be arranged that the oil fuel burning integrated combined cycle power generation method further comprises the step of producing oxygen using a pressure swing adsorption method, wherein the gasification step carries out the partial oxidation using the produced oxygen.
It may be arranged that the fuel producing step comprises a distillation separating step of separating the feed oil into a first light portion and a first heavy portion, and a solvent deasphalting separation step of separating the first heavy portion into a second light portion and a second heavy portion whose pitch softening point is higher than 140xc2x0 C., and that the gasification step disperses the second heavy portion into water uniformly to produce water slurry fuel, and then gasifies the water slurry fuel through the partial oxidation.
It may be arranged that the gas turbine power generation step carries out mixed combustion for simultaneously burning the light portion in a liquid phase and the syngas in a gaseous phase.
It may be arranged that the gas turbine power generation step separately carries out the power generation using the syngas and the power generation using the light portion, and that the power generation using the syngas is carried out as basic power generation, while the power generation using the light portion is carried out as auxiliary power generation for supplementing the basic power generation.